1. Field of the Invention
This invention relates to a memory hierarchy control method for computers which is particularly suitable for a large scale computer system wherein the request frequency of duplex loading of programs and/or data is high and a memory hierarchy is provided which consists of a real storage of large capacity, a disk/cashe unit and a disk unit.
2. Description of the Prior Art
In the past, programs and/or data to be written into a real storage are transferred from a peripheral storage to the real storage when a request for loading of the programs and/or data occurs. Consequently, the execution time for one program is prolonged and the amount of input/output transfer increases the danger of causing frequent occurrences of bottleneck at the input/output channel.
Analogous to the present invention, a technique has been available wherein paging and inputting/outputting in a virtual memory system are made virtual and programs and/or data are loaded on a real storage in advance. This technique, however, lacks a function characteristic of the present invention by which activity information for memory hierarchy control is acquired, such an allocation in a real storage as for reducing the physical input-output is automatically decided and executed on the basis of the activity information, and the activity information is displayed to permit the user to specify particular programs and/or data residing in the real storage. For this reason, this prior art technique is disadvantageous in that efficient use of the real storage is restricted and reduction effect of the physical input/output is poor.
In paging processing, on the other hand, a page replacement algorithm such as a least recently used (LRU) method or working set method is used wherein basically, the reference locality for program execution is utilized to load the most recently used programs and/or data on the real storage. In contrast therewith, the present invention is featured in that the size of a unit of transfer left out of consideration in the paging processing (while one page is fixed) is much accounted of in priority.